A number of clamps have been developed, three of which are disclosed in U.S. Pat. Nos. 3,276,800, 3,211,161, and 3,572,623. These three patents generally indicate the state of the prior art. One approach to the manufacture of these clamps utilizes casting. A cast clamp has significant torsional stiffness. However, this manufacturing process is costly if the units are not manufactured in high volume. Another approach contemplates plastically deforming a strip of material, usually steel, into a "U" shape. A hole is drilled into one of the arms of the clamp, and the hole is tapped to accommodate a set screw. When attached, the clamp is oriented so that the rounded portion is directly next to the tip of the supporting flange. This type of clamp can be manufactured inexpensively. However, unless made relatively thick, such a clamp tends to deform under heavy loading--the clamp tends to unbend at the line or lines where it was initially deformed.